Geranium is a native of the Cape Province in South Africa. It is commercially cultivated in France, Belgium, Spain, Morocco, Madagascar, Egypt, Reunion Islands, Congo, China, former USSR countries and to some extent in India and Israel for the production of the oil.
Pelargonium graveolens commonly known as Rose-scented Pelargonium, Rose-scented geranium or Rose geranium, is one of the many fragrant species of Pelargonium, belonging to the family Geraniaceae. Pelargonium graveolens is an erect, much-branched shrub with its attractive, strongly rose-scented leaves. The genus Pelargonium gets is name from the resemblance of the shape of the fruit to the beak of a stork, pelargos in Greek. The species name graveolens refers to the strong fragrance of the leaves, graveolens meaning strong-smelling in Latin.
Pelargonium graveolens is used in the production of geranium oil, which has a delightful floral fragrance, which makes it very pleasing to most people, and is highly priced for its very profound and strong rose like odour.
The oil of geranium, almost a perfume by itself, is stable and blends well with other fragrances lavender, patchouli, clove, rose, sandalwood, jasmine, juniper, neroli, bergamot and other citrus oils. It is widely used in perfumery and cosmetic products, and for the isolation of rhodinal, which forms part of most high-grade perfumes. It is also used as a substitute for the expensive scented oil of roses in the perfume trade. It's often used to scent soaps and detergents because, unlike many other essential oils, rose geranium's aroma profile is not readily affected by the alkaline nature of soap products.
There are several types of geranium oil, the main ones being Reunion or Bourbon, Algerian, Moroccan, and French. Reunion oil is very rich in citronellol and has a heavy rose and minty odor. Algerian oil has a delicate odor. Moroccan oil is similar to Algerian oil. French oil is thought to possess the finest rose-like odor. The concrete and absolute of geranium are also available commercially. Bourbon is considered the finest type, which is produced from the Rose Geranium, which is a hybrid of P. radens and P. capitatum. The name comes from the island, and the former French colony of La Réunion (previously known as Île de Bourbon), 800 km east of Madagascar, in the Indian Ocean. The island has the ideal climate and soil conditions for production of geranium. Bourbon geranium is cultivated and distilled exclusively on the island. The environment of Reunion has produced a strain of geranium with a very rich, rosy aroma. The geranium oil produced in other parts of the world may originate from different species.
The oil is composed chiefly of geraniol, citronellol, linalool, citronellyl formate. The oil also contains α-pinene, β-pinene, α-terpniene, myrcene, α-phellandrene, limonene, cis-ocimene, trans ocimene, p-cymene, terpinolene, cis-rose oxide, trans-rose oxide, menthone, trans-linalool, iso-menthone, carvophyllene, geranyl acetate, nerol, and geranyl formate, geranyl butyrate. However the chief constituent of the geranium oil is geraniol and citronellol. The citronellol: geraniol ratio is considered to be a distinguishing factor of the essential oil type that determines the quality of perfume. The Bourbon type of Reunion origin, the best quality commercial Geranium oil, has almost equal quantity of the Citronellol and Geraniol.
The essential oil is steam distilled from the leaves, stalks and flowers. The plant should be cut just before the flowers open and between 300 and 500 kg of plant material is required in order to obtain about 1 kg of essential oil. Most of the essential oil glands are found in its leaves. After cutting, the plants are partially dried to increase the yield of oil leaving less water to be vaporized and extracted from the plant material during the distillation. The essential oil in rose geranium leaves has the constituents, geraniol, linalool and citronellol, which are also present in rose oil. The well-balanced aroma of geranium's fragrance resembles that of rose with a musty, minty-green undertone.
In addition to its use in perfumery and cosmetics it also has pharmaceutical uses. The oil is non-toxic, non-irritant and generally non-sensitizing. It is reported to have a strong strengthening effect, effective in balancing emotions, raise energy reserves while soothing the mind and body. It is also described to balances sebum and therefore can suitable for all skin types.
The oil is also extensively used as a flavoring agent in most major food categories, alcoholic beverages and soft drinks.
The world production of geranium oil is estimated at 250-300 tonnes, whereas the demand is more than 800 tonnes annually. In India the requirement of oil is about 140 tonnes per year, whereas India is able to produce a meager quantity of about 5 tonnes geranium oil per year. As the production of Geranium oil is inadequate to meet the growing demand of the Indian perfumery Industry, the oil is met mainly by imports. Taking into consideration the high demand of this oil for cosmetic and perfumery industries in Indian as well world over, there is a large scope for the cultivation of this important plant in India.
Besides the use of Pelargonium graveolens plants as a source of essential oil, it is also cultivated for its floriculture value as well as for medicinal purpose. As a medicinal plant, geranium has traditionally been considered an astringent and used as a folk remedy in the treatment of ulcers. A terpine hydrate synthesized from geraniol is known to be an effective expectorant. Leaves are reported to have antifungal activity. Geranium is reported to repel insects because of its citronellol content.
Of late, the plant has also shown to have great potentials in phyto-remediation. The term “phyto-remediation” refers to an innovative technology that uses plants to remove and/or degrade environmental contaminants such as heavy metals and organic compounds. Pelargonium graveolens has been shown to tolerate high level of lead, copper and various hydrocarbon toxicity in soil.
From the foregoing thus it is apparent that either for the production of oil for various industries or the applications of Pelargonium graveolens for other various purposes, there is a huge demand for Pelargonium graveolens plants, which necessitates its large-scale cultivation.
Pelargonium graveolens is conventionally propagated by means of stem cuttings, or seed. The vegetative propagation by cuttings however, suffers from major disadvantages like relatively low numbers of plant multiplication, possibility of systemic pathogens getting propagated as well, limited time period during which plant can be multiplied, and relative high mortality.
Moreover propagation from seeds could change the genetic composition of the plant, which can cause undesirable changes with respect to its oil composition or yield. Which could make it unsuitable as a source of oil for perfumery or cosmetic or pharmaceutical industry for which it is chiefly cultivated.
The afore mentioned barriers associated with large scale propagation of Pelargonium graveolens can be overcome by in-vitro regeneration using micropropagation technique like tissue culture.
Micropropagation can be defined as in-vitro regeneration of plants from organs, tissues, cells or protoplast using technique like tissue culture for developing true-to type resultant plants of a selected genotype. In general tissue from a plant commonly known as explant, is isolated from a plant whose multiplication is desired to create a sterile tissue culture of that species in-vitro. From explant a culture is initiated, once a culture is stabilized and growing well in-vitro, multiplication of the tissue or regeneration of entire plant can be carried out. Shoots (tips, nodes or internodes) and leaf pieces are commonly used but cultures can be generated from many different tissues. Juvenile tissues generally respond best. Besides explant the chemical composition of the culture medium and the physical environment of cultures have been found to be of a great influence on the regeneration capacity, multiplication ration, growth and development of new plants in the culture system. Therefore one needs to optimize these factors for individual plant species.
Plant tissue culture is rapidly becoming a commercial method for large-scale propagation of the elite varieties, for plants difficult-to-propagate rapidly by conventional methods. Tissue culture is particularly useful for multiplication of plants, which are slow growing (turmeric, ginger, cardamom); cross-pollinated (coconut, teak, eucalyptus, cashew, mango and those which show wide variation in the progeny), male sterile lines (cotton, sorghum, pearl millet); newly free plants by meristem culture (sugarcane, potatoes, tapioca, etc).
Some work has been reported for micropropagation of different species of Pelargonium using tissue culture techniques. For instance U.S. Pat. No. 5,514,580 granted to Oglevee-O'Donovan et al. For “In vitro leaf petiole multiplication of Pelargoniums” describes a process for propagating Pelargonium domesticum varieties by tissue culture propagation of petiole sections taken from a mother plant. Wherein the effectiveness of the process at least in part is attributed to growth regulator selected from amino or benzyl—glucoside or glycoside the exemplary being benzylamino riboside.
However very limited work has been attempted for micropropagation of Pelargonium graveolens. 
For example study carried out by P. V. Lakshmana Rao, for in vitro plant regeneration of scented-leaved geranium Pelargonium graveolens, cited in Plant Science, Volume 98 (2), 193-198, 1994, discloses regeneration of plants from leaf segments involving callus formation on medium supplemented with 5 microM each of NAA, 2,4-D and 2.5 microM Kinetin and transferring of the primary callus to MS medium supplemented with 20 microM 2-isopentyl adenine, 10 microM kinetin and 108 microM indole-3-butyric acid or phloroglucinol for shoot regeneration. It is well known to those skilled in the art that the micropropagation method involving callus formation may not give true to type clones due to the possibility of somaclonal variation during callus formation. Moreover such indirect process would involve additional step of regeneration from callus and also additional media, therefore such process may not be very cost effective and also would be lengthy and time consuming.
Another study reported in Plant Science 155 (2000), 133-140, by Saxena Gauri, et al., describes an efficient in vitro procedure for micropropagation and generation of somaclones of rose scented Pelargonium graveolens Indian cultivar Hemanti of Algerian type. As reported the study involves direct and indirect regeneration of shoots from leaf and nodal explants. The best media reported for direct regeneration are, MS medium supplemented with 5 mg per liter of kinetin and 1 mg per liter of NAA for leaf explant, MS medium supplemented with 8 mg per liter of kinetin and 1 mg per liter of NAA for nodal explant and for indirect regeneration for nodal explants MS medium supplemented with 10 mg per liter kinetin and 1 mg per liter of NAA giving rise to callus formation. The rooting is carried out on half strength MS medium with 1 mg per liter of IBA. The study is however associated with certain drawbacks like it does not provide protocol for in vivo acclimatization of direct regenerated plants. Besides the main basis of the study is to develop somaclonal variants with the objective of extending area of cultivation beyond the conventional habitat, whereas the acclimatization of callus derived somaclones is provided limiting only to the north Indian plains and does not encompass the acclimatization in other geographical area with varied geographical conditions. Furthermore study is restricted only to Algerian variety.
As evident from above, of whatever limited work carried out on micropropagation of Pelargonium graveolens none of the studies are directed specifically towards Bourbon or Reunion type, which has high demand in commercial market for the fine premium quality of its oil. Therefore there remains the need to develop a highly efficient system for rapid multiplication of rose scented geranium Pelargonium graveolens of Bourbon or Reunion type by in-vitro micropropagation, which is devoid of drawbacks associated with prior arts, which can provide true to type resultant plants to maintain the genotype of the elite variety and give rise to large number of the planting material rapidly by cost effective method for the said genotype.